The elucidation of the structure, organization and function of photopigments (rhodopsin and color pigments) and their genes is of fundamental importance. Molecular cloning is a powerful method for studying the function and dysfunction of these visual pigments. Retinal mRNAs from rat, bovine and human eyes were extracted and purified. cDNAs made from the purified mRNAs were cloned by the G-C tailing procedure in the bacterial plasmid pBR322. Rat and bovine recombinant cDNAs libraries were established and are being screened for opsin sequences by hybrid selection and cell-free translation. The nature of the retinal binding site is also under investigation. Retinal binding through an apparent Schiff base linkage to calf Gamma-crystallin was found.